本文共 6010 字，大约阅读时间需要 20 分钟。

1.程序入口

package com.fy.day11.bank;/** * 银行案例的测试类（程序的起始） * @author fangyuan * */public class TestBank {   	public static void main(String[] args) {   			Bank bank =new Bank();//创建了一家银行网点	bank.welcomeMenu();		bank.getRandomCardNo();			bank.showAll();	}}

2. Bank类

package com.fy.day11.bank;/** * 银行类() * @author fangyuan * */import java.util.Scanner;import java.util.Random;public class Bank {   //中国建设银行		Scanner input = new Scanner(System.in);//实例变量（实例方法共享）	//保存已注册的用户数据	User[] users = new User[5];		int size = 3;	int currentIndex;		public Bank() {   				//第一行逻辑 初始化实例变量					User user = new User();		user.setCardNo("6222020200001234567");		user.setIdentify("11111111111111111");		user.setUsername("张三");		user.setPassword("123456");		user.setPhone("12399999999");		user.setBalance(2000.0);		users[0] = user;								users[1] = new User();		users[1].setCardNo("6222020200001234568");		users[1].setIdentify("11111111111111111");		users[1].setUsername("李四");		users[1].setPassword("123456");		users[1].setPhone("13999994444");		users[1].setBalance(3000.0);						users[2] = new User("6222020200001234560","11111111111111111","王五","123456","13666666666",5000.0);			}		//欢迎页	public void welcomeMenu() {   				System.out.println("-----------------------------------------------------------------------");		System.out.println("1.登录   2.注册");		System.out.println("请输入操作码：");		int choice = input.nextInt();		switch(choice) {   				case 1:			this.login();			break;		case 2:			this.register();			this.login();			break;		default:			System.out.println("输入有误，请重新输入！");						}	}		//登录	public void login() {   				System.out.println("请输入卡号：");		String no = input.next();		System.out.println("请输入密码：");		String pwd = input.next();				User u = check(no,pwd);		if(u != null) {   			this.showMenu(u);		}else {   			System.out.println("用户名或者密码错误");		}	}			//注册	public void register() {   				System.out.println("请输入姓名：");		String uname = input.next();						String id;	do {   		System.out.println("请输入身份证号：");		id = input.next();	}while(id.length() !=18);			String phone;	do {   		System.out.println("请输入电话号码：");		phone = input.next();	}while(phone.length() != 11);				System.out.println("请输入密码：");		String pwd = input.next();						System.out.println("请输入预存金额：");		Double money = input.nextDouble();						//根据用户输入的信息 + 随机卡号  完成对象的封装				String myCardNo = this.getRandomCardNo();				User user = new User();		user.setCardNo(myCardNo);		user.setUsername(uname);		user.setIdentify(id);		user.setPhone(phone);		user.setPassword(pwd);		user.setBalance(money);						//将该对象存储到users数组中//		if() {}//扩容判断		users[size] = user;		size++;		System.out.println("注册成功，您的卡号是：" + myCardNo);	}			public String getRandomCardNo() {   				String prefix = "622202020000";						Random random = new Random();				int r = random.nextInt(9000000);		System.out.println(prefix + (r + 1000000));				return null;	}		//验证	public User check(String no,String pwd) {   	for(int i = 0; i < size; i++) {   						//验证卡号和密码//		if(users[i] != null) {//非空判断						if( no.equals(users[i].getCardNo()) && pwd.equals(users[i].getPassword())) {   				//查找到该用户，用户存在				//存在				return users[i];			}		}	//}	   return null;//不存在}			//显示菜单	public void showMenu(User u) {   				int choice;	do {   		System.out.println("-----------------------------------------------------------------------");		System.out.println("---1.修改预留手机号 2.存款 3.取款 4.转账 5.查询余额 6.修改密码 7.注销用户  0.退出---");		System.out.println("请输入操作码：");		choice = input.nextInt();		switch(choice) {   		case 1:			System.out.println("执行开户");			break;		case 2:			System.out.println("执行存款");			break;		case 3:			this.withdrawal(u);;			break;		case 4:			System.out.println("执行转账");			break;		case 5:			System.out.println("执行查询余额");			break;			case 6:			System.out.println("执行修改密码");			break;		case 7:			this.cancel(u);			break;		case 0:			return;		default: 			System.out.println("输入有误，请重新输入！");			break;		}	}while(true);}				//注销	public void cancel(User user) {   				int index = size + 1;		//查找该用户所在的数组下标		for(int i = 0; i < size; i++) {   			if(users[i] != null) {   //非空判断									index = i;					break;								}		}		//移动该元素之后的每个元素				for(int i = index; i < size - 1; i++) {   						users[i] = users[i+1];					}				size--;			}//取款	public void withdrawal(User mine) {   		System.out.println("请输入取款金额：");		double money = input.nextDouble();			if(money < mine.getBalance()) {   			//可以取款			mine.setBalance(mine.getBalance() - money);			System.out.println("取款成功，当前余额为：" + mine.getBalance());		}else {   			System.out.println("余额不足");		}	}	public void showAll() {   		for(int i = 0; i < size; i++) {   					System.out.println(users[i].getUsername());				}	}}

3. User类

package com.fy.day11.bank;/** * 类的组成、私有属性、公共访问方法、构造方法 * 实体类：Entity   作用：存储数据 * @author fangyuan * */public class User {   		private String cardNo;//卡号	private String identify;//身份证号	private String username;//用户名	private String password;//密码	private String phone;//手机号码	private double balance;//余额			public User() {   }			public User(String cardNo,String identity,String username,String password,String phone,double balance, String identify) {   				this.cardNo = cardNo;		this.identify = identify;		this.username = username;		this.password = password;		this.phone = phone;		this.balance = balance;			}		public void setCardNo(String cardNo) {   		this.cardNo = cardNo;	}	public String getCardNo() {   		return this.cardNo;	}			public void setIdentify(String identify) {   		this.identify = identify;	}	public String getIdentify() {   		return this.identify;	}			public void setUsername(String username) {   		this.username = username;	}	public String getUsername() {   		return this.username;	}			public void setPassword(String password) {   		this.password = password;	}	public String getPassword() {   		return this.password;	}				public void setPhone(String phone) {   		this.phone = phone;	}	public String getPhone() {   		return this.phone;	}			public void setBalance(double balance) {   		this.balance = balance;	}	public double getBalance() {   		return this.balance;	}	}